The first 3.56 caused bricks. There is currently a class action lawsuit being started up regarding it because Sony won't fix the bricks. It is due to original PS3s having 256MB NAND and newer PS3s (including many Fats) having 16MB NAND. The 3.56 FW is installed to NAND, but since it is larger than 16MB, only a part of it gets installed onto NAND in newer models and the rest is installed to the HDD. Well, everything is fine (supposedly >_>) until you decide to upgrade your HDD. Since you only have part of the update on your NAND onw, the PS3 asks for the update file so it can install the other part on the new HDD. But the file is not recognized.
The silent v2 fixes this bug. But what happens if you don't have your original HDD? Well, v2 can only be installed via XMB. If you cannot get your PS3 up and running, there is no way to install the fix.